In some parts of the world, maximizing diesel production is the most important goal in petroleum refining.
One method of producing diesel is hydrocracking. Hydrocracking, may be designated as cracking under hydrogenation conditions such that the lower-boiling products of the cracking reactions are substantially more saturated than when hydrogen, or material supplying hydrogen, is not present. Although some hydrocracking processes are conducted thermally, the preferred processing technique involves the utilization of a catalytic composite possessing a high degree of hydrocracking activity. In virtually all hydrocracking processes, whether thermal or catalytic, controlled or selective cracking is desirable from the standpoint of producing an increased yield of liquid product having improved, advantageous physical and/or chemical characteristics.
In addition to the hydrocracking process, the diesel hydrotreating process is often necessary for making low sulfur diesel. Hydrotreating is a process wherein hydrogen gas is contacted with hydrocarbon in the presence of suitable catalysts which are primarily active for the removal of heteroatoms, such as sulfur, nitrogen and metals from the hydrocarbon feedstock. In hydrotreating, hydrocarbons with double and triple bonds may be saturated. Aromatics may also be saturated. Some hydrotreating processes are specifically designed to saturate aromatics. The cloud point of the hydrotreated product may also be reduced.
A conventional way to increase diesel production is to blend kerosene into diesel. However, increasing diesel production in this manner reduces the amount of kerosene (jet fuel) produced with little to no monetary advantage.
Therefore, there remains a need for processes for increasing the production of diesel without reducing the amount of kerosene produced.